


Gluttony

by Nanenna



Series: Devil's Threesome [2]
Category: Undertale (Video Game)
Genre: Alternate Universe - Demons, Alternate Universe - Monsters Weren't Sealed Underground, Alternate Universe - Underfell (Undertale), Anachronism, Body Horror, Demons, Ecto-Genitalia (Undertale), M/M, Mildly Dubious Consent, Multi, Non-Human Genitalia, Oral Fixation, Patchwork AU, Plot What Plot/Porn Without Plot, Sans/Underfell Papyrus/Underfell Sans (Undertale), Sibling Incest, SpicyKustard (Underfell Ship), Spit Roast, Threesome, Threesome - M/M/M, Underfell Papyrus (Undertale), Underfell Sans (Undertale), no editing we die like men
Language: English
Status: Completed
Published: 2020-05-01
Updated: 2020-05-01
Packaged: 2021-03-01 19:35:22
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,568
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23952421
Author URL: https://archiveofourown.org/users/Nanenna/pseuds/Nanenna
Summary: Sir Edge and his brother, Red, are not mere messengers, and yet here they are delivering a message to a demon lord! Too bad the demon lord's not home and they're stuck dealing with his lazy brother instead.
Relationships: Papyrus/Sans (Undertale), Papyrus/Sans/Sans (Undertale), Sans/Sans (Undertale)
Series: Devil's Threesome [2]
Series URL: https://archiveofourown.org/series/1540084
Comments: 24
Kudos: 75





	Gluttony

**Author's Note:**

  * Inspired by [Underfell](https://archiveofourown.org/external_works/763602) by Vic the Underfella. 



> Dub-con tag is due to lack of communication, which is of course a cardinal sin.

A pair of double doors were pushed open by a short demon, who then stood to the side and announced, “Sir Edge and Sir Red, in the service of Queen Undyne the Undying, here with a message on her behalf,” loudly to the seemingly empty room.

“’m not akchully a knight,” Red mumbled with a roll of his eye pips.

“HUSH, BROTHER,” Edge ordered, his own pips scanning over the room. In the center, raised on a dais, was a large, ornate chair overflowing with pillows, blankets, and what appeared to be a tapestry that may have once covered the only bare space on the wall behind the chair. The veritable mountain of cushions seemed to be the only thing keeping the tiny skeleton monster Edge hadn’t noticed before lounging in the oversized chair from falling out.

“sorry, pals, your princess is in another castle.”

“WHAT?” Edge raised a brow, an easy feat when the claw scars through his other brow made it near immobile.

The short, round skeleton sighed and waved a hand at them. “you’re here to talk to demon lord papyrus, right? he’s not in right now, leave a message after the beep.”

Edge and Red stared at the strange skeleton, unsure what to do. When a minute passed and no “beep” was forthcoming Red finally lost his patience, “so where is he? how long’ll he be? an’ who the hell’re ya?”

The strange skeleton sighed again, then shifted to slouch in a slightly more upright position. “really gonna make me work, aren’t you? the name’s sans, sans the skeleton.” He winked at them. “papyrus is my bro.”

Red snorted, “ya don’t look much like a demon lord.”

“RED!”

“what? he don’t!”

He really didn’t, all the demons they’d seen scurrying about had fangs, claws, horns, armor, and sharp, piercing eyes. They looked like they’d fit in back in their own kingdom rather than with this short, round, straight toothed skeleton with the large, round, drooping orbits. “THAT’S NO REASON TO BE RUDE!”

“so ya gonna answer my questions? where’s yer bro and when’ll he be back?”

“he’s off doing the whole allies thing. that was his idea, and i gotta say it’s a pretty sweet deal up until some king or other actually needs our help. so you can run along back to your queen and tell her the message is returned to sender, or you can hang around here until he gets back.”

“HOW LONG WILL HE BE?”

Sans shrugged, “dunno, a week maybe?”

It would take that long just to return to Queen Undyne, they were better off waiting here for Lord Papyrus’s return. Edge told Sans as much.

“cool, i’ll have someone prepare a room for you. in the mean time, you two want something to eat? you must be hungry after traveling so far and i could use a snack myself.”

* * *

Lunch had been surprisingly delightful despite being full of more grease than Edge could “shake a stick at,” as Sans has put it. Now Edge and Red were looking forward to a nice long, hot soak to wash away the dirt of traveling. Another demon servant, or perhaps the same one from earlier, was guiding them to their room. They stopped in front of a door and grinned broadly up at them, a suspicious twinkle in their eyes. Edge went in first but found nothing strange about the room. It was large and spacious, one large bed with its headboard against one wall stood as the eye catching centerpiece of the room, a pair of chests at its foot. Against the other walls and sprinkled throughout the room were a wardrobe, a desk with a matching chair, a vanity with its own matching chair, a pair of low settees, and a high backed arm chair with matching ottoman. Edge also noted a door off to the side, and to their right heavy curtains hinted at a window behind them.

Red started prowling about the room, poking his nose hole into all the nooks and crannies while Edge reached for the wardrobe, curious to see if a change of clean clothes had been provided for them.

“well look who it is.”

Red and Edge both jumped and whirled around, the bed suddenly sporting an indolently lounging occupant it hadn’t a moment before.

“SANS! WHY ARE YOU SNEAKING AROUND IN OUR ROOM?!”

“funny thing, that. this is actually my room, turns out every last one of the guest rooms is in the middle of repairs or renovations. and will you look at that, there’s only one bed. guess we’ll have to share it.” He ended this strange statement with a very obvious wink.

Edge looked the demon up and down, taking him in from his drooping eye socket lids to his blank, lazy smile to his wrinkled, sloppily tied tunic to the sleeves that nearly covered his tiny hands to the scuffed shoes he was wearing on the bed. Everything about him seemed harmless and innocent. Edge didn’t doubt for one minute that Sans wasn’t any of those things. “ARE YOU SUGGESTING WE SHARE YOUR BED WITH YOU?”

Sans shrugged, “only if you want to, i’m sure one of the rooms could be whipped into decent shape if you insist.”

Edge glanced to Red, standing across the bed from him and ready attack or flee if Edge ordered it. Red gave Edge a wide, toothy grin, his eye sockets wide, an eager gleam to his pips. Edge looked back at Sans, who’s lazy, devil-may-care expression hadn’t changed. “THIS WILL BE ACCEPTABLE.”

“cool.” Sans kicked off his shoes, thankfully they landed beside the bed and not on the counterpane, then he squirmed out of his clothes, tossing them aside as carelessly as his shoes.

“oh goodness, i’m jus’ so tired from all that travelin’ i think i’ll just go straight to bed.” Red was no better, hopping in place as he rushed to pull off his boots and gambesons, leaving them where they fell around him.

Edge rolled his eye pips, he would not be so eager and careless as these two. He carefully took off his light armor and set it atop one of the chests, then he just as carefully removed his clothes and folded them neatly next to the armor. By the time he was finished the other two were sitting on the bed, eye pips locked on him like a hawk on its prey. He briefly looked at the scattered, rumpled piles of clothing and armor and promised himself he’d scold his brother later. For now he climbed up onto the massive bed where the grubby demon and his considerate host were patiently waiting.

Sans sat up, grinning eagerly up at Edge, “oh my, two big, strong heroes. are you here to stab me in all my deepest, darkest, most vulnerable places with your big, long, hard swords?”

“fuck yeah we are,” Red agreed a little too eagerly, then dropped his voice into a low, husky timbre in an attempt to sound sultry, “gonna stab ya with our swords all. night. long.”

Edge grabbed Red’s skull and pushed him face first into Sans’s pelvis. “PUT YOUR MOUTH TO BETTER USE.”

Red gave a muffled reply but otherwise didn’t move. Judging from the way Sans gasped and arched his spine Red had chosen to get to work while still hunched over awkwardly. And in Edge’s way.

Edge rolled his eye pips, then nudged Red’s hunched form. “GET OUT OF THE WAY.”

“alright, alright. i’m movin’, god.”

“oh, should I call him that too?”

“YOU MAY IF YOU WISH,” Edge magnanimously conceded. Red snickered as he settled himself between Sans’s legs, then went back to work, his tongue curling around Sans’s pubic symphysis and his claws delicately tracing over Sans’s ischium. Edge settled himself next to Sans and leaned down to pull him into a kiss, one hand cradling the back of his skull. He noted his hand nearly covered the entirety of the small monster’s skull, the other wandered down to fondle of his ribs. Sans responded delightfully, leaning up into the kiss as his own hands explored over Edge’s ribs and spine.

Sans’s fingers delicately drifted over Edge’s sacrum, mapping out where every ridge and dip was. Then his fingers lined up with Edge’s sacrum holes and dug in all at once, plugging Edge up nicely. He gasped, the hand on Sans’s skull clenching while the arm supporting him shook with the effort of holding himself still. He fell his dick summon, already half hard and getting harder as Sans wriggled his finger tips in their new homes.

“what the fuck?”

Everything seemed to freeze. Sans pulled his fingers form Edge’s sacrum so he could prop himself up on his elbows and look down at where Red was sitting back from between his legs.

Edge likewise sat back as he looked at his brother with concern. “WHAT IS IT?”

Red pointed down between Sans’s legs, where an overgenerous amount of searingly bright, icy blue ecto had formed from his ribs down to his knees. “that’s a mouth.”

“uh… yeah?” Sans said as if it were the most obvious thing in the world and for the life of him he couldn’t figure out why Red was so thrown for a loop.

Edge quickly moved down the bed to wedge himself next to his brother. Just as Red had said between Sans’s legs, right where some sort of sexual organ would usually be manifested, was a mouth. Plump, symmetrical lips a darker blue than the rest of his flesh, almost sky colored, were barely parted, something that looked like drool leaking from one corner. Unable to resist his curiosity, Edge reached down and delicate parted the lips, inside were blue teeth, strangely straight and even. He poked them, pulling a gasp from Sans in the process, the teeth were pliant. False teeth formed from ecto.

“i’m gonna kiss it.” Red swatted Edge’s hand out of the way, completely ignoring his outraged his. He leaned down, then back, tilted his head, leaned closer again, re-angled his head once, twice more…

Edge huffed in impatience, and from where Sans was watching propped up on his elbows he laughed faintly. “need a map there, buddy?”

“OR PERHAPS AN INSTRUCTION MANUAL?”

“yeah, yeah, laugh it up.” Red sat back and grabbed Sans’s hips, twisting him onto his side. Then with a wide grin he hefted one of Sans’s thighs over his shoulder and bent back over to press his teeth to Sans’s lips.

Judging from the airy gasps and the way Sans squirmed Red’s kiss must be doing something for him. Edge moved back up to Sans’s skull. His intent was to go back to kissing him, but Sans reached for his dick, and who was Edge to refuse him? Edge let Sans have what he wanted, following his lead when Sans hooked a hand around his hips and pulled him close enough for his teeth to press to the tip of his dick. Edge groaned at the feel of Sans’s hot breath washing over him mixed with the tingle of their magics meeting.

“holy shit, ya got two tongues?!”

Edge wanted to bang his head against the nearest wall, “MUST YOU CONTINUALLY INTERRUPT US?”

“didja not hear the part about him havin’ two fuckin’ tongues?!”

“uh…” was Sans’s eloquent response, his teeth still on Edge’s dick sending the vibrations of his voice right through him.

“this is so fuckin’ hot, i’m gonna fuck this weird ass mouth so hard.”

“it’s not an ass mouth,” Sans said with a chuckle.

“I WISH YOU’D GO BACK TO KISSING HIM, SHUT YOUR RIDICULOUS MOUTH UP.”

While Red was adjusting his own position, Sans opened his mouth and took Edge’s dick in. It took all of Edge’s self control to not buck his hips or just grab Sans’s skull and start fucking his mouth. Edge groaned and threw his head back, his legs trembling with the effort of holding himself still for Sans. He rested a hand on Sans’s skull, just wanting to touch him some way as he simply let himself enjoy his ministrations, blocking out the ridiculous filth spewing from his brother’s mouth.

Sans seemed quite distracted by Red’s attentions, his face screwed up in concentration as he moaned around Edge’s dick. Edge ran his phalanges over Sans’s skull, “MAY I FUCK YOUR MOUTH?”

Sans paused and looked up at Edge, then gave the barest nod. He opened his mouth a little more and flattened out his broad, clever tongue, letting Edge push in until he was down to the root. He started pumping, hard and fast so Sans wouldn’t be left choking for long as he chased his pleasure.

“oh fuck, oh FUCK!” Red gasped from down the bed, going still. Of course he came first.

Sans moaned again somehow, then as if intent on getting Edge to cum too he pulled Edge’s hips close and swallowed. It was enough to tip Edge over the precipice he’d been steadily working towards. Edge tried to pull out, but Sans’s grip on his hips was like steel. Sans swallowed a few times more, almost rhythmically, like he was trying to draw Edge’s orgasm out.

Edge whimpered and tried pulling out again, with one final suckle Sans let him go. He felt spent, like a rag that had been freshly washed and wrung out, ready to just flop over and fall asleep. His dick was already dissipated before his body even hit the bed.

Red groaned from where he’d flopped over, likely he’d gotten similar treatment with Sans’s weird crotch mouth. “jus’ let me die right here.”

“NO,” Edge insisted, though the only thing he could be bothered to move was a hand, which weakly pointed towards the ceiling. “WE NEED TO CLEAN UP BEFORE THE MESS DRIES.”

“are you saying i wasted even a drop of perfectly good magic?” Sans asked in the most offended tone. That may well be true, but Edge and Sans and very likely Red were all sweaty messes nonetheless.

“WE NEED TO TOWEL OFF AT THE VERY LEAST.”

“i’m not movin’ even if the world starts endin’.”

“you sure? the pillows and blanket are more comfortable up here.” Sans patted the pillow and turned down blanket next to him.

“WE’RE ALL SWEATY AND GROSS,” Edge insisted weakly.

“one sweaty nap isn’t going to kill you, just get a little rest and then go take that bath i interrupted. we’ll get fresh sheets on the bed before dinner’s done.”

“sounds like a plan to me,” Red slurred as he grumpily crawled up the bed. Sans helpfully pulled back the blankets more, all three of them shimmying down between the sheets like a sweaty, disorganized pile of bones. Then Sans patted the blankets back into place.

“WAIT,” Edge said blearily, trying in vain to sit back up, “YOU DIDN’T GET YOUR PLEASURE.”

“don’t worry none, i got off plenty,” Sans assured with another wink, he gently pushed on Edge’s sternum to keep him in place.

Not that it really mattered, both Red and Edge were out like lights. Sans chuckled and settled in, a flurry of various sized tongues licking over a wide array of teeth. He’d definitely have to order a feast for tonight’s dinner, these two certainly earned it. And who knew, perhaps that evening they’d have a nice little dessert.

**Author's Note:**

> I have no idea why I made Sans tell anachronistic jokes, but they amused me so I left them in. *shrug emoji* It took me way too long to finish this, but it's done! Ahhh! Baby's first body horror: mouths where they don't belong. I bet y'all thought Sans's sin would be sloth (and it will, just not in this one) but have you seen the little trash goblin in action? Boy likes him some food, so lets have him be a gluttony demon. Poor Fell boys have no idea what kind of trap they just fell into.


End file.
